Dana and Chris leave on their bicycles from Union High School at the same time. Dana rides east traveling at 15 mph and Chris rides west traveling at 9 mph. How much time will pass before they are 48 miles apart?

Astudent draws two parabolas on graph paper. both parabolas cross the x-axis at (–4, 0) and (6, 0). the y-intercept of the first parabola is (0, –12). the y-intercept of the second parabola is (0, –24). what is the positive difference between the a values for the two functions that describe the parabolas? write your answer as a decimal rounded to the nearest tenth